The present invention relates to a pump and more particularly to a low-capacity pump for dispensing liquids such as perfumes, and cosmetics or pharmaceuticals.
A conventional pump generally comprises a body made of a plastics material and defining a metering chamber provided at a first end with an inlet valve via which a liquid is fed in from a container, and at a second end with an outlet valve carried by the inner portion of a spray tube mounted to move axially by co-operating with a helical spring.
However, in such a pump, the inlet valve comprises a ball that is made of metal, and that is received inside the pump body in the metering chamber, as are the return means which are generally constituted by a spring that is also made of metal.
Therefore, liquid which remains even for a short time in the metering chamber comes into contact with metal elements, which gives rise to risks that the properties and in particular the quality of the liquid might be modified.
Furthermore, the pump body is made of an opaque plastics material in order to mask the internal metal elements. Unfortunately, the container is often constituted by a flask made of glass or of a transparent plastics material that allows the body of the pump to show through, which gives rise to an appearance that is unsatisfactory.
Furthermore, pumps also exist in which the return means are constituted by a helical spring disposed outside the metering chamber.
However, in such a pump configuration, the return spring is maintained in a slightly compressed state around the outer portion of the spray tube, in particular by its top end abutting against the end wall of a cavity provided in a dispensing head capping the end of said tube.
Therefore, such a pump configuration does not make it possible to separate the pump from the dispensing head safely since the spring would then not be secured to any part, and might be lost, in particular during storage or automatic transfer operations.
In addition, assembly operations are complex because they require prior mounting of the spring.
An object of the present invention is to solve the above-noted technical problems satisfactorily.
The invention achieves this object by means of a pump characterized in that inlet valve comprises, in particular, a ball that is not made of metal, while the outer portion of the spray tube is provided with a laterally-extending shoulder against which a first end of said spring abuts in wedged manner.
In a particular embodiment, the body and the ball are made of a plastics material that is transparent or at least translucent.
According to an advantageous characteristic, the pump further comprises an inner bushing engaged in said body to close off said chamber around the inner portion of the spray tube, the end wall of said bushing serving to receive in abutment the second end of the spring.
According to another characteristic, the inner end of said bushing forms an abutment for the outlet valve carried by the inner portion of said tube.
According to yet another characteristic, said ball is made of glass or of polypropylene, while the pump body is made of polypropylene.
In a particular variant, the face of the shoulder that is in contact with a first end of the spring is plane and is perpendicular to the axis of the spray tube.
In another variant, the face of the shoulder that is situated closer to the outer end of the spray tube is beveled.
Preferably, said shoulder is formed over the entire periphery of the tube.
The pump of the invention makes it possible to transfer the liquid without any contact with any metal element whatsoever, thereby preserving the qualities of the liquid and simplifying the manufacturing and assembly operations, while offering cost that is low.
Furthermore, all of the components of the pump that are disposed inside the container are made of a material that is translucent or transparent to light, which considerably improves the overall appearance insofar as the pump is almost invisible in the liquid.